- Each patient will routinely receive 4 puffs of 25 mcg salmeterol /250 mcg fluticasone (Seretide Evohaler 250; GlaxoSmithKline Inc. Evreux, France) every 12 hours until the discontinuation of ventilator. Each patient will also routinely receive 1 vial of Combivent (ipatropium bromide 0.5 mg and salbutamol sulfate 2.5 mg) every 6 hours and be injected with intravenous methylprednisolone 40mg every 8 hours in the initial 3 days.The use of short acting bronchodilator in an as-needed basis is not restricted. According to the Raw data determined every 8 hours, individualized dosing group will receive an additional 4 puffs of 25 mcg salmeterol /250 mcg fluticasone plus 4 puffs of fenoterol if the value is higher than personal target Raw (Once it coincides with regular dosing period of salmeterol/fluticasone, only fenoterol will be added). No such extra dose will be given to fixed dosing (control) group regardless of Raw value.